The process of reading a JPEG image involves multiple steps, configuring structures, and running decompression. The processor writing a JPEG is similar, involving configuring structures and running compression. Once decompressed, JPEG data is available for manipulation in memory.
- [Instructor] Even with a lib jpeg library available, … reading and writing a jpeg image is a complex task … involving lots of variables, configuration, and process. … So it helps to break everything down into steps. … This code reads the sample jpeg file 05-02-image.1, … which is specified at line seven. … It decompresses the image data and then stores it in memory. … Now the seven steps to reading a jpeg file are: … Number one, open the input file at line 16, … which is just standard C code. … Number two at line 26 is to configure the dcinfo structure … for decompression. … Number three at line 35 is to decompress the file, … which is done by the jpeg_start_decompress function. … Next at line 38, some information about the image … is gathered and output. … At line 46, a data structure is created … to hold the raw image data read … from the decompressed image file. … At line 58, the raw data is read and stored … in the while loop. … At this point you can manipulate the image stored …
Author
Dan Gookin
Released
10/1/2019- Finding, installing, and linking libraries
- Accessing and generating XML data
- Working with JSON
- Working with the libcurl library
- Text programming
- Reading, writing, and manipulating JPEG images
- Working with PNG images
Skill Level Advanced
Duration
Views
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Introduction
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Using the exercise files1m 2s
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Working with the code2m 45s
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1. Setup and Configuration
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Understanding libraries2m 50s
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Finding a C library2m 44s
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Installing a library4m 15s
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Liking a library: IDE4m 10s
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2. Data Structures
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Understanding XML2m 23s
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Accessing XML data3m 26s
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Generating XML data3m 57s
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Working with JSON2m 39s
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Accessing JSON data3m 10s
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Reading JSON data3m 46s
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Creating JSON output3m 35s
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3. Web Access
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Testing libcurl2m 3s
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Fetching a web page3m 47s
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Saving web data3m 31s
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Sending data2m 35s
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4. Text Programming
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Working with wide characters3m 19s
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Building an ncurses program2m 27s
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Controlling the text screen2m 32s
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Making color text2m 56s
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Exploring ncurses input4m 6s
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5. Computer Graphics
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Accessing a JPEG2m 31s
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Manipulating JPEG images3m 5s
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Working with PNG images3m 57s
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Modifying a PNG image2m 26s
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Conclusion
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Writing your own library4m 19s
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Next steps1m 17s
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Video: Reading and writing JPEG images